Stabilization of amorphous calcium carbonate by controlling its particle size.

Amorphous calcium carbonate (ACC) nanoparticles of different size are prepared using a flow system. Post-synthesis stabilization with a layer of poly[(α,β)-dl-aspartic acid] leads to stabilization of the ACC, but only for particles <100 nm. Larger and uncoated particles readily convert into the crystalline forms of CaCO₃. This shows that ACC is intrinsically stable below 100 nm.